/*
 * Copyright (c) 2011, the Dart project authors.
 * 
 * Licensed under the Eclipse Public License v1.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 * 
 * http://www.eclipse.org/legal/epl-v10.html
 * 
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */
package com.google.dart.tools.ui.internal.util;

import org.eclipse.core.runtime.Assert;
import org.eclipse.jface.viewers.ColumnLayoutData;
import org.eclipse.jface.viewers.ColumnPixelData;
import org.eclipse.jface.viewers.ColumnWeightData;
import org.eclipse.swt.SWT;
import org.eclipse.swt.events.ControlAdapter;
import org.eclipse.swt.events.ControlEvent;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.graphics.Rectangle;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Table;
import org.eclipse.swt.widgets.TableColumn;

import java.util.ArrayList;
import java.util.List;

/**
 * A special composite to layout columns inside a table. The composite is needed since we have to
 * layout the columns "before" the actual table gets layouted. Hence we can't use a normal layout
 * manager.
 */
public class TableLayoutComposite extends Composite {

  /**
   * The number of extra pixels taken as horizontal trim by the table column. To ensure there are N
   * pixels available for the content of the column, assign N+COLUMN_TRIM for the column width.
   */
  private static int COLUMN_TRIM = "carbon".equals(SWT.getPlatform()) ? 24 : 3; //$NON-NLS-1$

  private List<ColumnLayoutData> columns = new ArrayList<ColumnLayoutData>();

  /**
   * Creates a new <code>TableLayoutComposite</code>.
   */
  public TableLayoutComposite(Composite parent, int style) {
    super(parent, style);
    addControlListener(new ControlAdapter() {
      @Override
      public void controlResized(ControlEvent e) {
        Rectangle area = getClientArea();
        Table table = (Table) getChildren()[0];
        Point preferredSize = computeTableSize(table);
        int width = area.width - 2 * table.getBorderWidth();
        // TODO(scheglov) by some reason I always had horizontal scrolling, so reduce width
        width -= 2;
        // Subtract the scrollbar width from the total column width
        // if a vertical scrollbar will be required
        if (preferredSize.y > area.height) {
          Point vBarSize = table.getVerticalBar().getSize();
          width -= vBarSize.x;
        }
        layoutTable(table, width, area, table.getSize().x < area.width);
      }
    });
  }

  /**
   * Adds a new column of data to this table layout.
   * 
   * @param data the column layout data
   */
  public void addColumnData(ColumnLayoutData data) {
    columns.add(data);
  }

  // ---- Helpers
// -------------------------------------------------------------------------------------

  private Point computeTableSize(Table table) {
    Point result = table.computeSize(SWT.DEFAULT, SWT.DEFAULT);

    int width = 0;
    int size = columns.size();
    for (int i = 0; i < size; ++i) {
      ColumnLayoutData layoutData = columns.get(i);
      if (layoutData instanceof ColumnPixelData) {
        ColumnPixelData col = (ColumnPixelData) layoutData;
        width += col.width;
        if (col.addTrim) {
          width += COLUMN_TRIM;
        }
      } else if (layoutData instanceof ColumnWeightData) {
        ColumnWeightData col = (ColumnWeightData) layoutData;
        width += col.minimumWidth;
      } else {
        Assert.isTrue(false, "Unknown column layout data"); //$NON-NLS-1$
      }
    }
    if (width > result.x) {
      result.x = width;
    }
    return result;
  }

  private void layoutTable(Table table, int width, Rectangle area, boolean increase) {
    // XXX: Layout is being called with an invalid value the first time
    // it is being called on Linux. This method resets the
    // Layout to null so we make sure we run it only when
    // the value is OK.
    if (width <= 1) {
      return;
    }

    TableColumn[] tableColumns = table.getColumns();
    int size = Math.min(columns.size(), tableColumns.length);
    int[] widths = new int[size];
    int fixedWidth = 0;
    int numberOfWeightColumns = 0;
    int totalWeight = 0;

    // First calc space occupied by fixed columns
    for (int i = 0; i < size; i++) {
      ColumnLayoutData col = columns.get(i);
      if (col instanceof ColumnPixelData) {
        ColumnPixelData cpd = (ColumnPixelData) col;
        int pixels = cpd.width;
        if (cpd.addTrim) {
          pixels += COLUMN_TRIM;
        }
        widths[i] = pixels;
        fixedWidth += pixels;
      } else if (col instanceof ColumnWeightData) {
        ColumnWeightData cw = (ColumnWeightData) col;
        numberOfWeightColumns++;
        // first time, use the weight specified by the column data, otherwise
// use the actual width as the weight
        // int weight = firstTime ? cw.weight : tableColumns[i].getWidth();
        int weight = cw.weight;
        totalWeight += weight;
      } else {
        Assert.isTrue(false, "Unknown column layout data"); //$NON-NLS-1$
      }
    }

    // Do we have columns that have a weight
    if (numberOfWeightColumns > 0) {
      // Now distribute the rest to the columns with weight.
      int rest = width - fixedWidth;
      int totalDistributed = 0;
      for (int i = 0; i < size; ++i) {
        ColumnLayoutData col = columns.get(i);
        if (col instanceof ColumnWeightData) {
          ColumnWeightData cw = (ColumnWeightData) col;
          // calculate weight as above
          // int weight = firstTime ? cw.weight : tableColumns[i].getWidth();
          int weight = cw.weight;
          int pixels = totalWeight == 0 ? 0 : weight * rest / totalWeight;
          if (pixels < cw.minimumWidth) {
            pixels = cw.minimumWidth;
          }
          totalDistributed += pixels;
          widths[i] = pixels;
        }
      }

      // Distribute any remaining pixels to columns with weight.
      int diff = rest - totalDistributed;
      for (int i = 0; diff > 0; ++i) {
        if (i == size) {
          i = 0;
        }
        ColumnLayoutData col = columns.get(i);
        if (col instanceof ColumnWeightData) {
          ++widths[i];
          --diff;
        }
      }
    }

    if (increase) {
      table.setSize(area.width, area.height);
    }
    for (int i = 0; i < size; i++) {
      tableColumns[i].setWidth(widths[i]);
    }
    if (!increase) {
      table.setSize(area.width, area.height);
    }
  }
}
